Front end for excavating machines



Oct. 2, 1951 I o, vmso 2,569,458

FRONT END FOR EXCAVATING MACHINES Filed Nojv. 17, 1947 2 Sheets-Sheet 1 d flam czsm, INVENTOR,

Oct. 2, 1951 r. o. DAVIDSON FRONT END FOR EXCAVATING MACHINES 2 Sheets-Sheet 2 Filed NOV. 1'7, 1947 A T T OR/VE Patented Oct. 2, 1951 UNITED STATES PATENT; OFFICE" FRONT END FOR EXCAVATING-MACHINES Trevor 0.- Davidson, Milwaukee, Wis, assignpr to Bucyrus-Erie Company, South Milwaukee, Wis., acorporation of Delaware V I 7 Application November 17, 1947,- Serial No. 786,446

3 Claims. (01. 214-435) movable in approximately a circle about this shaft.

The usual construction of the digging mechanism of power shovels, dredges and the like, consists of an inclined boom, the lower end of which rests on the main structure of the machine, the

upper end being supported by guys which are generally anchored to a mast, which in turn is anchored to the rear end or part of the structure carryin the hoisting machinery. At approximately the middle of the boom a saddle'block is hinged, through which passes the dipper handle under control of the shipper shaft on which the saddle blockis pivoted. The actual digging element, the'dipper, is attached to the outer end of the dipper handle. There is also attached to the dipper a rope, or ropes, which pass over a sheave or sheaves at the outer end of the boom and thence to the hoisting machinery. The boom is usualy inclined about 45 to the horizontal. Means are provided for causing the dipper handle to move in and out through the saddle block 1 In the past, two modifications of the abovedescribed conventional construction have been employed in order to provide greater digging force from a given rope pull at lower positions of the dipper and/or to reduce torsional stress produced in the boom by the dipper handle due to swinging inertia of the dipper and side-thrust of the bank: (1) The dipper handle has been slidably mounted on a fixed boom which terminates at the shipper shaft, and the dipper hoist line has been passed over a sheave mounted at the end of a short movable mast pivoted at the end of the boom. See U. S. Patent No. 2,015,629, issued September 24, 1935, to Samuel Lippincott Griswold Knox.

(2) The dipper handle has been hinged or jointed at its rear end to a movable boom pivoted on the main frame of the machine and terminating at the hinge or joint, and the dipper hoist line has passed over a sheave mounted at the end of a long fixed mast pivoted on the main frame. See U. S. Patents Nos. 2,139,254 and 2,139,255 issued December 6, 1938, to Kenneth R. Bixby.

. There are, however, a number of disadvantages with each of these modifications.

On the one hand, in the Knox design, pivoting 2 the .mast at the end of the boom makes for high tension in the mast hoist line and high compression stresses in the mast when it is lowered to obtain high digging forces in a low pit, and accordingly the sheave supports, the mast, the boom,

and the boom braces must be heavily built. Fur-- thermore, substantial torsional stresses are still imparted by the dipper stick to the boom through.

the saddle block and shipper shaft, again making it necessary to have a heavy boom and boom On the other hand, in the Bixby design, which has a fixed mast and a movable boom with dipper handle jointed on the boom, the reach of the dipper is shortened in low digging positions because the dipper stick must be drawn in with the boom: to obtain the better digging component, and the dumping range is limited to points far out in front of the machine. Furthermore crowding movement requires more work, since at each pass of the dipper, notonly the dipper handle, but also the boom and actuating arm must be moved. Furthermore,- since the rear end of the Bixby dipper handle is.

fixed to the end of its supporting boom, the boom must be drawn in to a point substantially above the mast when digging low and/or close in to the mast, and accordingly the arc in which the dipper handle can swing sideways inside the mast is seriously restricted by the legs of the mast. Further-- more, since the Bixby dipper handle swings sideways about an axis perpendicular to the dipper handle, the dipper is free, when the dipper is raised to dumping position, to swing sideways in a wide arc whose radius is the full length of the dipper handle and accordingly in that position there is danger of interference between the dipper handle and the converging legs of the mast.

Accordingly it is the principal object of my in-- vention to improve over the Knox and Bixby front-end constructions in various ways, includ-' ing:

(1) Provision of a mounting for the boom and dipper handle in which torsional stresses in the boom due to swinging inertia and side thrust are eliminated without twisting of the dipper handle 3 affected by increase of the digging component in low positions of the dipper.

(4) Provision of a front end construction in which side swing of the dipper handle in low digging positions of the dipper will not be limited appreciably by the legs of the mast.

(5) Provision ofa variable support for the dipper-hoistzline, sheave, said supportbeing movable: to provide greater diggin force in low positions of the dipper, being mounted independently of the boom, and being so oriented that compression stresses in the sheave supportare reduced.

(6) Provision of a front end construction having the advantages without the above-mentioned disadvantages of previous front-end designs.

In addition to my principal objects, above stated, I have worked out a number of noveland; useful details, which will be readily evident as the description progresses.

My invention consists in the novel parts, and inthe combination and arrangements thereof, which are defined in the appended claims, and of which two embodiments are exemplified in the accompanying drawings, which are hereinafter particularly described and. explained.

Throughout the description, the same refer ence number is applied to the samemember or to similar members.

Figure 1 is a plan view of one embodiment of my "invention, in which the main supporting structure is shown conventionalized.

Figure 2 is a side elevation, of the same embodiment, taken along the line 2--2 oi Figure 1.

Figure 3 is an enlarged interior side elevation, partly insection, of the short boom, and the, crowd machinery, ofthe-same embodiment, taken along the line 3-3 of Figure 1.

Figure 4 is a side elevation, similar to-Eigure 2, of a second embodiment of my invention.

Referring to Figures 1 to.3-, it will: bev seen that. l l is the main frame. of aneexcavator, revolviable on. a. propelling base. Hi. It aboomswivelly mounted at its: foot. on the base, and inclined upwardly. therefrom.. The main irame. H also; carries structure i3, whichmaybe. (as: shown) in the; form of a conventional Aeframe or, may take the form of a. mast; Orany; other onven ional; form. [4 is astrut. exten in irQm th top oi. e: Aefliame 13 to. theouter end of hev boom. 12, a onnec ed er to y o ar hichpermi e hoqm to swivelabout its axis within said, collar.. [.6 is, adipper handle, carrying at its outer enda dipper l1. I8; is a shipper-shatt', located. on: the bcomadjacent the juncture of strut l4 and boom; l 2 and piv lly S pporting saddle block 19 within which reciprocation of the dipper handle [6; is eifected by two ropes 20v andjZJ passing. around sheaves 22 on the shipper shaft, andjanchored respectively to the front. and rear endsof the dipper handle [6. Ropes 20 and 2 l pass from the dipper handle l6 around sheaves 22 thencesto, drum 2.3 at the foot of. the boom l2, to which drum they are eventually dead-ended, Gear 24 on drum 23 is actuated through pinion 25a, by gear 25 which is in turn. driven by, conventional motor 26 (shown schematically), these being sup.- ported preferably on the, boom, and preferably adjacent. the foot of the. boom. Mast 2,1, supported at its foot on mainframe Ll, preferably; on spread pivots, 28 at the front of the main frame adjacent the swivel supportv of, the boom, extends beyond the outer end of the boom and supports dippe h n sheaves, 1,9. re s onmember 311 between Arframe i3. and the outer end of mast 21 supports the mast at a fixed'inclination. Dipper hoist lines 31 extend from the dipper I! over sheaves 29 to a conventional winch 32 mounted on the main frame I I.

It will be seen that this construction results in reduced stresses in the boom, which can accordingly be built lighter, thereby reducing swinging moment and increasing efficiency. Compression stresses. in the boom l2 are. reduced, since only the dipper handle I6 is supported thereon, the dipper hoist line 3| being supported independently by mast 27. Torsion stresses in the boom I2, due to swinging inertia of the dipper and side thrust of the bank, are eliminated by having the boom swivellymounted on the main frame H.

i Since, the. drum- 23 which controls the crowd ropes 20 and 21' is mounted on the boom and swivels with. in any twisting of crowd ropes 20 and 2| (or other forms of crowd drive) due to side motion of the dipper handle is avoided. Furthermore, since the dipper handle is not fixed but is longitudinally slidable with respectto. the boom, it is possible to dig close to the. machine when the boom is above or nearly aligned with the mast so that side swing of the dipper handle is practically unrestricted by the legs. of the mast. And-lastly, due to the fact that the. dipper: handle swings sideways about theaxis of the boom (instead of an axis perpendicular to the;- dipper' handle), we see that, as the dipper handle is raised to come more nearly into line with theboom, side swing of the dipper handle is more: and more restricted until it becomes a mere tilting motion of the dipperabout the boom axis; hence as the dipper handle is raised between the:

' upwardly converging legs of the mast, interference between the dipper handle and the mast is automatically prevented;

Turning now to Figure 4, We see that in my second embodiment, I have substituted tackle-40 actuated by Winch 41- onmain v frame H for: tens-ion member 35) tosupport the mast 21- at various inclinations (shown dotted) above and below the inclination of boom I2, thereby pro viding a decreased or increased digging compo nent as; desired. Excessive compression stresses: in the mast, when it is dropped to a lower position to produce an increased digging component for lower positions of the dipper, are avoided by pivoting the mast on the main frame rather than high on the, boom, thereby maintaining a substantial angle of incidence between tackle and the mastZ'l.

Having now described and illustrated two forms; of myv invention, 1' wish it to be understoodthat inv n on, is ot. to. be l mit d; t specific forms or arrana rnent v of parts. hereinhe r escribed, and shown.

I. claim:

1. In an excavating. machine the combination of: a base; an elevated, structure thereon; a hat winch; an, upwardly inclined boonrmounted at, its foot on the base for free swivelling movement; b t l ngitudinal axis. of the. oom;v support means for. the boom.,,extending 11cm the, elevated structure to, approximately the upper end of the, boom and s-wivelly, connectedtotheboomior said, swivelling movement ofthe boom; a mastmounh. ed at itsfooton. th base and? inclined. upwa dht therefrom with its upper end extendin appreciably beyond, the upper end of the boom;. sup: port means fOr the mast distinct from the boom support means, and extending from, the elevated structure to the upper end of the mast; a sheave carriedby the, mast, approximately at its; upper end; 'a dipper handle; a digging dipper carried by the handle; support means connecting the dipper handle to the boom at approximately the upper end of the boom, said support means including a transverse horizontal shipper shaft located approximately at the upper end of the boom and a saddle block pivoted on said shipper shaft for swinging in a vertical plane, the handle being mounted in said saddle block for reciprocating movement with respect to the boom along the axis of said handle; means to reciprocate the handle assembly; and a hoist line, distinct from the boom support means and extending from a direct connection to the dipper and handle, over the sheave, to the winch.

2. An excavating means according to claim 1, further characterized by the fact that the support means for the boom has a normally fixed length and that the mast is normally approximately parallel to the boom.

3. In an excavatin machine the combination of: a base; an elevated structure thereon; a hoist winch; a dipper handle; a digging dipper carried by the handle; support means supporting the dipper handle on the base for lateral swinging of the handle, for pivotal movement of the handle in a vertical plane, and for reciprocation of the handle with respect to the handle support means along the axis of the handle; said handle supportmeans including an upwardly inclined boom mounted at its foot on the base, and support means for the boom extending from the elevated structure to approximately the upper end of the boom; a mast mounted at its foot on the base and inclined upwardly therefrom with its upper end extending appreciably beyond the upper end of the boom; support means for the mast distinct from the boom support means and extending from the elevated structure to approximately the upper end of the mast; a sheave carried by the mast approximately at its upper end; means to reciprocate the handle; and a hoist line, distinct from the boom support means, extending from a direct connection to the dipper and handle assembly, over the sheave, to the winch.

TREVOR O. DAVIDSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

